Acoustical oscillator, principally organ pipe



Feb. 20, 1940. N. P. RJJARNAK 2,191,058

ACOUSTICAL OSCILLATOR, PRINCIPALLY ORGAN PIPE Filed Jul 14. 1936INVENTOR.

Patented Feb. 20, 1940 UNITED STATES PATENT OFFICE ACOUSTICALOSCILLATOR, PRINCIPALLY ORGAN PIPE Niels Poul Robert Jarnak, Hillerpd,Denmark 1 Claim.

The present invention refers to the class of acoustical oscillatorswhich consists of a resonator formed principally as a tube in whichstanding waves can be caused by an air current flowing through amouth-piece so as to strike the lip or tongue (labial or reed) at oneend of the resonator.

In former acoustical oscillators of similar kind, the mouth-piece hasexclusively served the purpose of leading the air current to the lip ortongue of the resonator.

This invention involves the formation of the mouthpiece in such a waythat it acts as a resonator the resonance frequency of which inproportion to the resonance frequency of the real resonator is 3:2 orabout 3:2. Experiments in connection with the invention have indicatedthat sounds can thus be produced of exceptional strength as comparedwith the amount of energy contained in and carried by the air current,and, further, of quite equisite timbre which is principally remarkablebecause it produces an aural impression of purity, and if severalconcordant sounds are produced simultaneously by means of severalacoustical oscillators in accordance with the invention the differentsounds are found to blend well with one another.

The best efiect is obtained if the proportion between the resonancefrequency of the mouthpiece and that of the resonator has the abovementioned ratio 3 :2, but experiments have proved that the effectintended to be produced by the invention can also be obtained quitewell, even if this proportion is somewhat above or below this value.

An entirely satisfactory theoretical explana tion of the effect obtaineddoes not exist, but it should be noted that it is not likely that theeffect is caused exclusively by the character of the overtones andcombination tones caused by the addition of the chamber of resonance,the resonance frequency of which is 3/2 times the frequency of thefundamental tone.

It is rather assumed that the effect is partly caused by the specialcondition of movements of the air molecules which are created round thelip or tongue of the resonator.

The invention is chiefly of importance to organ pipes. The drawingindicates an example of its 5 application to a flue pipe in accordancewith the invention.

I is the resonator of the organ pipe formed principally as a tube, thelength and kind (open or stopped) of which determines the pitch which 10resonance frequency of which is 3/2? times the 20 resonance frequency ofthe resonator I. In the form as shown, the resonator l is open, and thelength of the mouth-piece must therefore be about 2/3 the length of theresonator I.

The invention may also be applied to stopped 25 flue pipes in whichcase, assuming an open. and a stopped pipe of the same pitch, the lengthof the mouth-piece of the stopped pipe must equal the length of themouth-piece of the open organ pipe.

The same refers to the reed pipes (open or stopped) and to all otheracoustical oscillators, the production of sound occurs in a similar way.

What is claimed is:

An acoustical oscillator of the type of an organ 88 pipe comprising afundamental oscillation resonator, a mouth piece acting as an auxiliaryoscillation resonator, and an oscillation producing means therebetween,the resonance frequencies of the fundamental oscillation resonator andthe auxiliary oscillation resonator being substantially in theproportion of 2:3.

NIELS POUL ROBERT JARNAK.

